Table 1.
The algicidal activity of the peptides against various marine algal strains.
Figure 1.
Morphological changes of rapidoflagellates in the presence of peptides.
C. marina (A) and H. akashiwo RA-018 (B) cells incubated without (1) or with HP(2–20) (2), HPA3 (3), and HPA3NT3 (4) peptides each at IC90 for 2 min. Bar: 100 µm for all panels.
Figure 2.
Time-dependent changes of C. marina cells in the presence of HPA3NT3.
After 4 µM of peptide of was introduced to algal cells, cell morphology was digitally recorded by video. The images were extracted from video files at the indicated times. Arrows and arrowheads indicate the damaged regions of the plasma membrane and the released chloroplasts, respectively.
Figure 3.
Algicidal effects of peptides against dinoflagellates and diatoms.
(A and B) P. minimum (A) and C. polykrikoides (B) cells without (1) or with HPA3 (2) and HPA3NT3 (3) each at each IC90. (C) Density of surviving cells at the indicated times. (D) S. costaum cells incubated without (1) or with 128 µM HPA3 (2) and 256 µM HPA3NT3 (3) for 3 days at 20°C. Bars: 50 µm for panels A and B and 100 µm for panel D.
Figure 4.
The selective algicidal action of HPA3NT3 in co-cultivations of harmful and harmless algal cells.
(A) The changes of cell density in co-cultures of S. costatum (square) and H. akashiwo (circle) in the absence (filled and 1) or presence (open and 2) of 2 µM HPA3NT3. (B) Images of surviving cells after 6 h of incubation with and without 2 µM HPA3NT2. (C) The changes of cell density in co-cultures of S. costatum (square) and P. minimum (triangle) in the absence (filled and 1) or presence (open and 2) of 8 µM HPA3NT3. (D) Images of surviving cells after 24 h of incubation with and without 8 µM HPA3NT2. Bar: 50 µm for panels B and D.
Figure 5.
Localization of TAMRA-HPA3NT3 in serial sections.
(A) C. marina cell treated with 2 µM of TAMRA-HPA3NT3 for 2 min. (B) P. minimum cell treated with 4 µM of TAMRA-HPA3NT3 for 30 min. The images were automatically recorded on 12 planes from the top to bottom of the cell. Numbers in left top of each panel represent the distance of focus from the top of the cell.
Figure 6.
Mode of action of HPA3NT3 in algal cells.
(A) Uptake of SYTOX green in H. akashiwo and S. costatum cells treated with HPA3NT3. (B) Concentrations of chlorophyll a in cell treated with HPA3NT3.
Figure 7.
Hemolytic effects of peptides.
Peptides with indicated concentrations incubated for 1 h with red blood cells collected from Sebastes schlegeli, and the released hemoglobin was then calculated.
Figure 8.
In vitro clearance of red tide.
40 µg/mL of HPA3NT3 was mixed with H. akashiwo of 1×108 cells/mL, and sedimentation of algal cells or clearance of turbid seawater continuously recorded.